Starting in the Name of Allah, The Most Beneficent, The Most

Merciful

A channel is a path between two communication devices

Channel

Signaling transmission method Medium used Bandwidth: amount of data transmitted

in a fixed amount of time Direction(s) in which signal can flow Noise, attenuation, and distortion

characteristics

Characteristics

Signaling transmission methodAnalog: continuous varying waveforms to carry dataDigital:a.Two different values of electrical voltage or current b.On/off light sourcec.Frequently preferred because less susceptible to noise and interference

Directions Point to point channels

a. Simplex: channel passes data in one direction only

b. Half-duplex: transmits data one direction at a time (walkie-talkie)

c. Full-duplex: transmits data in both directions simultaneously (telephone)

Channel Organization

Multipoint: broadcasts messages to all connected receivers larger number of recievers

Transmission medium

MediazMaterials carrying the signala.Consists of two types:

i. Physical: wire cable ii. Wireless: Air

Physical Transmission Media

Twisted-pair cable

Coaxial cable

Fiber-optics

Twisted-pair cable

Cabling is a type of wiring in which two conductors of a single circuit are twisted together for the purposes of canceling out electromagnetic interference (EMI) from external sources

Twisted-pair cable

c

twisted-pair cable twisted-pair wire

Coaxial cable   A type of cable that has an inner

conductor surrounded by a tubular insulating layer, surrounded by a tubular conducting shield. Many coaxial cables also have an insulating outer sheath or jacket.

Fiber-optics

Its a flexible, transparent fiber made of high quality glass (silica) or plastic, slightly thicker than a human hair. It can function as a waveguide, or “light pipe”, to transmit light between the two ends of the fiber

Fiber-optics

Fiber-optics

Optical fibers are widely used in fiber-optic communications, which permits transmission over longer distances and at higher bandwidths (data rates) than other forms of communication. Fibers are used instead of metalwires because signals travel along them with less loss and are also immune to electromagnetic interference.

Fiber-optics

Wireless Transmission Media

 Broadcast Radio a. Distribute signals through the

air over long distance b. Uses an antenna c. Typically for stationary

locations d. Can be short range

Wireless Transmission Media

Cellular Radioa. A form of broadcast radio

used for mobile communication

b. High frequency radio waves to transmit voice or data

Wireless Transmission Media

Microwaves a. Radio waves providing high

speed transmission b. They are point-to-point (can’t be

obstructed) c. Used for satellite communication

Wireless Transmission Media

Infrared (IR) a. Wireless transmission media that

sends signals using infrared light- waves

Wireless Transmission Media

Infrared (IR) a. Wireless transmission media that

sends signals using infrared light- waves